Electric phonograph



Fatentecl June 27, 1933 nairnn STATES ADOLPH A. THOMAS, OF YORK, N. Y.

ELECTRIC PHONOGBAPI-I.

Original application filedDecember 16, 1926, Serial No. 155,116. Dividedand this application filed May 16, 1931. Serial No. 537,858.

This invention is for an electric phonograph in which the reproducer armnormally rests on a support adapted to operate'suitable switch mechanismwhen the arm is removed and replaced. In the broad aspect of myinvention, this switch mechanism may control any circuit of the electricphonograph apparatus, such as a current supply for the reproducer. Inone form of my invention, when the reproducer arm rests in idle positionon its support, a movable member of the support holds a current supplyswitch open so that no electricity is wasted. When the reproducer ismoved to playing position,suitable spring means actuates the controllingmember of the support to close the switch, so that the machine is inoperative condition. I The novel features and practical advan tages ofmy invention will be understood from a description of the accompanyingdrawing, in which r Fig. 1 is a perspective view of an electricphonograph provided with my automatic switch control; I f Fig. 2 is anenlarged cross-section of the support for the reproducer arm and theassociated switch device; and i Fig. 3 is a simplified circuit diagramof suitable operative connections between the pickup and theloudspeaker.

A cabinet G contains suitable phonographic mechanism which need not beshown or described in detail, since it forms no partof the presentinvention. It is enough to say that a turntable 10 is mounted over thetop board 12 for supporting a sound record 13. The turntable shaft 14 issupposed to be driven by a motor (mechanical or electric) mountedbeneath the top board 12. There will, of course, be a brake for startingand stopping the turntable, and a motor switch if an electric motor isused, but I neednot illustrate these parts because they are obvious. Anelectric pickup or reproducer 15 is mounted on a movable arm 16, whichis preferably a light tube in which the circuit wires for the reproducermay be concealed.

There are various types of phonograph pickups in themarket,-electromagnetic, microphonic and electrostatic,and since theseare well known, I need not set forth any structural details thereof. Itwill therefore reproducer arm 16 is mounted for vertical and horizontalvmovement in any practical way. In Fig. 1, the rear end of arm- 16 ispivoted on a horizontal .pin' or bearing 17 carried by a swivel post,18, which is rotatably mounted on asuitable base member 19 fixed on thetop board 12. The horizontal pivot bearing 17 allows vertical movementsof arm 16, and the swivel post 18 permits the arm to swing horizontallyover the turntable. Any other practical form'of mounting for thereproducer arm 16 may be adopted.

The electric impulses produced by the operation of pickup 15 aresuitably amplified to actuate a loudspeaker diaphragm 20, which in thepresent instance is'mounted in a rectangular frame 21 at the front ofthe cabinet. The diaphragm 20 is represented as a tensioned vibratorysheet connected to a suitable driving-unit 22, which may be ofv anyapproved type or design. The circuit 23 of pickup 15 includes a primarycoil 24: and a rheostat 25, which is operated by a rotary hand knob 26on top of the motor board 12 to control the volume of reproduction. Thereproducer circuit 23 is fed by a suitable source of current, indicateddiagrammatically by a battery 27. The primary coil 24; is in transformerrelation to an amplifying secondary coil 28, which is connected to theelectric. driving unit 22. In Fig. 8 the electricpickup 15 isrepresented diagrammatically aslbeing of the microphone type, comprisinga vibratory member 29 connected to the stylus arm, a fixed member 30(the microphone casing or rear wall), and a mass of carbon granules 81.When the member 29 vibrates in the playing of a record, the variationsin the electrical resistance of themicrophone cause current impulses inprimary coil 24, andthese impulses are amplified in the secondary coil28 to energize the driving unit 22/ Any other practical transmissionconnections between pickup 15 and diaphragm 12 by screws 33 orotherwise. The top of post 32 carries a pair oi? spring fingers 34,which are shaped to receive the reproducer arm 16 and firmly hold thesame clamped down a ainst the top of the post. A simple way to mount thefingers 34 on post 32 is to secure them to a ring or collar 35, which isscrewed to the post. This mounting of the spring ingers 34 allows themto be rotatably adjusted. on the supporting post 32 at the correct anglewith respect to the pivotal mounting of reproducer arm 16. In otherwords, the support is so positioned on the top board 12 that thereproducer arm 16 is held clear or the turntable 10, usually to theright side thereof. in the hollow supporting post 32 is mounted areciprocable rod or plunger 36, which may conveniently be made hardinsulating material, such as bakelite, vulcanized rubber and the like.To the lower end of rod 36 is secured a metal piece 37 adapted to span apair of switch contacts 38 mounted on an insulating plate 39, which issecured to the underside oi the motor board 12 by screvs 40 orotherwise. Any other practical way 01 mounting and insulating the switchcontacts 33 may be used. A coil spring 41 surrounds the rod or plunger36 and normally tends to push it upward to hold the connecting piece 37in firm engagement with contacts 38 for closing the reproducer circuit23. The normal closing position of contact piece 37 is indicated by thedotted outline 37" in Fig. 2. The lower end of coil spring 41 bearsagainst a shoulder 42 in the hollow post 3:2 and the upper end of thespring presses against a collar 43 fixed on plunger 36.

lVhen the reproducer arm 16 is oil the support 32, the coil spring 41holds the rod 36 in such position that the upper rounded end of the rodprojects upwardly to a point roughly indicated by the dotted line 36. ilhen the arm 16 is pushed down between th spring fingers 34 as shown inFig. 2, the plunger 36 is depressed and the connecting piece 3? opensthe switch contacts 38, thereby breaking the circuit of battery 27, orany other circuit associated with the operating mechanism of thephonograph. The inher cnt tension or spring fingers 34 is such that theyovercome the weaker spring 41 and hold the reproducer arm 16 firmlypressed down, so that the connecting piece 37 remains in open positionas long as the pickup arm rests on support 32. When the pickup isremoved from its support to play a record, the compressed coil spring 41instantly lifts the plunger 36 and closes the associated switch 3738.

Although I have shown and described a specific form of support andswitch control for the pickup arm 16, 1 want it understood that myinvention is not limited to the details set forth. Various changes andmodifications are possible within the scope of the appended claims. Thisapplication is a division of my copending case filed December 16, 1926,Serial Number 155,116.

I claim as my invention: 7

1. In an electric phonograph, the combination of a top board having aturntable and a pivot post, an arm connected at one end to said post forhorizontal swinging movement and at its other end carrying an electricreproducer adapted to play records on said turntable, said arm andreproducer being movable into and out of operative relation to a recordon the turntable, a support on said top board for holding said arm inrest position, said support having a movable part adapted to'be actuatedby said arm in one direction, spring means for automaticallyactuatingsaid' part in the opposite direction when the arm is removedfrom the support, and a switch automatically controlled by said movablepart for rendering a circuit of said phonograph operative'when the armis moved into playing position. 7

2. In an electric phonograph, the combination of a top board having aturntable and a pivot post, an arm connected at one end to said post forhorizontal swinging movement and carrying at its other end an electricreproducerfor playing records on said turntable, said arm andrcpro-ducerbeing movable into and out of playing position, a support on said topboard adapted to hold said arm in rest position, switch mechanismassociated with said support for controlling a circuit of saidphonograph, and means for automatically operating said switch mechanismwhen the reproducer arm is removed from and replaced on said sup port,said means including a reciprocable spring-pressed plunger.

3. In an electric phonograph, the combination of a top board havinga-turntable and a pivot post, an arm connected at one end to said postfor horizontally swinging movement and at its other end carrying anelectric reproducer adapted to play records on said turntable, said armand reproducer being movable into and out of operative relation to arecord on the turntable, a support on said top board for holding saidarm in rest position, a switch for controlling a circuit associated withsaid reproducer, a movable member associated with said support forautomatically opening said switch when said arm is placed on saidsupport, and spring means for automatically actuating said member toclose said switch when the arm is removed from said support.

4. In an electric phonograph, the combination of a top board having aturntable and a pivot post, an arm connected at one end to said post forhorizontal swinging movement and carrying at its other end an electricreproducer for playing records on said turntable, said arm andreproducer being movable into and out of playing position, a support onsaid top board adapted to hold said arm in rest position, a movablemember adapted to be depressed by the reproducer arm when the latter isplaced on said support, spring means for raising said member when thereproducer arm is removed from said support, and switch mechanismcontrolled by the movements of said member for rendering a circuit ofsaid phonograph operative when the arm is moved into playing position.

5. In an electric phonograph, the combination of a top board having aturntable and a pivot post, an arm connected at one end to said post forhorizontal swinging movement and at its other end carrying an electricreproducer for playing records on said turn-. table, a hollow support onsaid top board for holding said arm in restposition, a switch forcontrolling a circuit associated with said reproducer, a verticallymovable member carv ried by said support andadapted to be'depressed bythe reproducer arm to open said switch when the arm is placed on saidsupport, and a spring for automatically raising said member and therebyclosing said switch when the reproducer arm is removed from saidsupport.- I

6. In an electric phonograph having a top board, the combination ofapivot post on said top board, a reproducer arm mounted on said pivotpost and movable into and out of playing position, a support mounted onsaid top board and adapted to hold said arm in rest position, saidsupport comprising a fixed hollow post and a member vertically movablein said post, said member being pushed down by the weight of thereproducer arm, spring means for normally rais ing said member, andswitch mechanism arranged below said top board and controlled by themovements of said member for rendering a circuit of said phonographoperative when the arm is moved into playing position.

7. In an electric phonograph, the combination of a horizontally andvertically movable arm carrying an electric reproducer, a h'ol

